Resistance.



T. VON ZWBIGBERGK.

RESISTANCE. v APPLICATION FILEDNOV. 2a, 1906. annwnn JULY 6, 1903.

912,267. v -Patented Feb. 9,1909.

'f WITN EISSES: I I

WM W W ,dlstance between the grids around the insulation, minimiz ng the danger of an arcmg you, ZWEIGBERGK, OF PRESTON,'ENGLAND, AssIeNoa, BY-MESNE ASSIGNMENTS,

TO GENERAL ELECTRIC COMPANY, A-GGRBQBATION OF NEW YORK.

nest semen.

. I i Specification of Letters Patent.

Patented Feb. 9,1909.

Applicationfiled November 28, me, win maniacs. Renewed July c, 1908. Serial No. 442,2'18.

To all whomit may concern: 4. i Be it knownthat I, Tnons'rnn VON Zwnre- BERGK, residing at Preston, in the countyaof jLancaster, England, have invented a cer-' tainnew and useful Improvement in ltesist ances, of which the following is 'aiull, clear,

and exact description, reference being had to the acconi anying drawings.

This inventionrelates-to resistanceadapted to be usedin connectionwith thecontrol of electric motors.

One of the objects is to prov de resistance in the form of a series :of superimposed" grids insulated 'from each other (except at certain connectin points) andeverystrip of each grid positive y andindependently supporte whereby'a long path tor the current -provided'through the various portions of each 'd in series, while the whole structure constitutes a firm and rigid box which .withstand considerable abuse. Another object isto so form the grids that am le ventilationis provided.

other object is to rotect the insulation,

against damage while a owing a considerable short circuit.

.The inventlon includes also a simple and.

eflicient meansfor making connections between consecutive grids.

' v These features are hereinafter more par 1 ticularly described, as summarized in ,the claims.

In" the drawings, Figure 1 is a horizontal section through the resistance box, showing one of the rids in plan; Fig. 2 is a side elevation of t e com ete resistance box. Fig. 3 is an enlarged ragmentar side elevation .from the point 3 in Fig. 1. ig. 4 is a vertical cross sectionthrough several of the grids, as'on the line 4 of Fig. 1. ,tive view of one of the connecting latcs.

,ters, A represents a suitable base ,or support adapted to besecured as desired,0n the" underside of a car, for example; Depending ,from this support are a series of bolts 13 rigidly connected with the supporting plate.- As shown, there arefour of these bolts.

Fig. 5 is ap'erspec- Referringto the drawings by re erence letvide the g'rid into a continuous serpentine conductor of comparatively small cross section. The bolts .15 pass through holes 0 in the corners of each grid, the grids being mounted one'uponythe 'otherwith interposed insulation D, and the .bolts "being insulated from the grids by tubular insulation K.

Fig. 2 .shows asuitable cover plateE ex- .tending across the bottom grid. Nuts 12 screwing onto the-bolts B clamp the varioiis parts together.

As shown in in .2, the .ends of tha i As shown, suitable jaddiztional insulation F, with interposed-strips 0t T ES ()FFIGE. l

V THORSTEN .55, xmetal G to give firmness, may be mounted :forks care all of t e sameheight, including;

the larger outermost forks, while bet zthese-ends he-cross bars fiIQsQfdQSB shown at 0, Figs. 1 and 3. This enables tilation between the grids, as wellnas between the strips of each grid. c

The insulat on D between the sists preferably =.of strips ofhmica whichextendacross theends a having holesthrough which the bolts B ass. are of sufiicient thic ssatO prevent their bethecurrent arcing from one grid toathe other, or leaking across the end of the mica,'while at the same time protecting the mica from damage at its edge,l 'form each grid with the outwardly beveled edge 0*. This allows one .face of the (the lower face in the drawing) to over ang the mica, protecting-it from damage, -while,-owingto the bevel on the adjacent. rid

a art't tgleakage or arcing 0 the mica isrprev'ented .aroundthe edge I havereferred to .the edges of the 'ds as having the bevel of. As shown, this vel is formed on a reverse curve. It'may beunade in any manner which will enable one surface of the grid to overhang the other. If the grids'had vertical sides and the mica terminated flush with them, or inside of their outer sma that there would be leakage and arcing. 0n the other -hand, if to prevent this the ,mica projects beyond the grids, the mica is ends of .each grid-strip to be ,independently" supported, while givingample space for .ven-

ing punctured by the current. To prevent the two grids are such a-distance edgefithe space between the grids would be so heightms grids con liable to be damaged by contact from the outside. My invention obviates both difiiculties and allows the advantage sought to be obtained.

To make the desired connection between the consecutive grids, I provide a flat stri of copper H which at the proper points is oubled around the mica and contacts with the grid above it and the grid below it. This strip is shown in Fig. 5. It has a hole It, through which the bolts B with the tubular insulation K passes. This copper strip forms a very efiective connection between the consecutive grids andiseasily mounted at desired points. N 0 special provision-need be made for it and it is Cprotected bythe overhanging edge of the a jacent grid. a

The outside connections to the resistance are made by binding osts L which have openings Z for the attac ent of the circuit wires and are clamped by set screws Z on flat lugs 0 extending from the grids. Each grid has two of these'lugs, located respectively at the beginning and end of the series conductor which the grid provides. The binding posts will usually be attached to the top and bottom grids so that the current may pass in series through the whole box; though, if desired, they may be attached at other points, leaving some of the grids out of service.

The construction described enables the resistance to be built up with as many grids as desired, into a very compact resistance-box.

Every strip of each grid is rigidly supported and the insulation protected, so that while the construction is very cheap it is likewise extremely durable. Moreover the ventilation and arc-preventing features make the resistance box very efficient in service.

Having described my invention, I claim: 1. A resistance composed of a series of grids formed with slots alternately from 0p- .posite sides, the strips thus produced being thicker across the endsof said slots, strips of insulation between the grids and extending across the thicker portions thereof, whereby the strips are independently supported while ventilation space is provided.

2. A resistance composed of a series of grids each grid having slots from opposite edges, whereby a series of forks are produced, the headof each fork being of substantially the same height throu hout-while intermediately the forks are of essheight, strips of insulation extending across such heads between the grids, and means for holding the whole structure together in the form of a rigid box.

3. A resistance composed of a series of grids, each rid having slots from op osite edges, where y a series of forks are pro uced,

the heads of the forks being thickened continuously across the ends of the slots, thereby strengthening the grid and providing a raised seat for insulation, strips of insulation resting stantially at the'four corners ofthe grid,

holes through said bosses, and four rods passing through said holes for holding the whole structure together in the form of a rigid box.

5. A resistance composed of a series of members and interposed insulation, the edge of the member on outside of the insulation overhanging it and on the other side terminating short of it.

6. A resistance composed of a series of grids separated by insulation, each grid having an edge overhanging the adjacent grid, the insulation between the grids projecting beyond one grid and being protected by the overhang of the other.

7. A resistance composed of a series of members whose edges are formed to consecutively overhan and insulation placed between the mem ers and extending beyond the adjacent edge of one member and protected by the adjacent member. s

8. A resistance composed of a series of grids with beveled edges, insulation between the grids overhanging the inner edge of one adjacent grid and terminating short of the outer edge of the other adjacent grid.

9. A resistance composed of a series of grids formed with slots alternately from opposite sides, the edges of the grids between the ends of the slots being formed to consecutively overhang, strips of insulation placed between the grids and extending across the slots and projecting beyond the edge of one adjacent grid and protected by the edge of the other adjacent grid.

10. A resistance composed of a series of gridseach grid having slots from op osite edges, whereby a series of forks are pro uced,

the same height, strips of insulation extending across such heads between the grids, the heads on one side of the insulation overhanging it and on the other side terminating short 1 f it.

11. A resistance composed of a series of grids, with intermediate insulations, connecting U-shaped strips extendin on to opposite sides ofthe insulation and around the edge thereof and contacting with adja-' cent grids, said strips having holes through them, and rods passing through said holes for holding the grids together and the-strips in place 12. In a resistance, the combination of a suitable support and rods carried thereby, a series of grids hav-ing holes throughwhich said rods pass, said grids having beveled sdgessnd, strips offinsulation between the grids havin holes through which the rods ass, said insulation overhanging the edge of.

no adjacent end: terminating short of 'the edgefoffthejconsecutivegrid;

Q13; 'n aresista'nce, the combination of a upport, a: series of rods extending there;-

om, insulation around said rods, a series of 'd's'ifnounted, on such r'ods'rand insulation,

tion and havingfholesthroilghfwhich the rods andtnhnlarinsnlationf ass; 145 1 11 a resistance,=lt e combinationvof a a uitahle siipportland' rods carried thereby, a

- saidirods pass;.said grids having. s ots fronr oppos teedges, the heads-of the forks thiis' godjuc' b ng insulation extending across such v havingholes thronghjwhich saidrods pug.

series efgridsjhavingholes thr'ou' h which i [oftsubstantially the same? ight-and---Iiaving beveled edges strips of;

heads.

and terminating short ofthe edge of theother adjacent grid and a metallic coxineoting stra passing around the edge of some of the insu ating strips and contacting with the grids on opposite sides thereof.

15. In a resistance, the'combination of s.

suitable support and rods carried thereby, a

series of grids having holesthrou h which said rods pass, said grids having s ots from opposite-edges, the heads of the forks thus produced being of substantially the same thickness, which thickness is greaterrthan that ofthe intermediate portions of the forks ;'and strips 'of insulation extending'across such heads and baring holes throu'gh'which 1 said-rods-pa'ss; eachof said'strips'at its outer edgeia'nd ends'overhangingthe edge of one frnoas'rsu'vos ZWEIGBERGK.

' MeJisuus, I

overheng ingf 'th'e edgeof one adjacent E -ws rson.

acent terminating short, of the I 4 3 111 testinion -whereof,-Ihereunto affix my 'signatnre ihtt epresence cf two witnesses. 

